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Figure 15.UN03 P generation gametes Sperm Egg This F 1 cell has 2 n  6 chromo- somes and is heterozygous for all six genes shown ( AaBbCcDdEeFf ). Red  maternal; blue  paternal. Each chromosome has hundreds or thousands of genes. Four ( A, B, C, F ) are shown on this one. The alleles of unlinked genes are either on separate chromosomes (such as d and e ) or so far apart on the same chromosome ( c and f ) that they assort independently. Genes on the same chromo- some whose alleles are so close together that they do not assort independently (such as a, b, and c ) are said to be genetically linked. D C B A F E d c b a f e D C B A F e d E f c b a